.TH std::stof,std::stod,std::stold 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::stof,std::stod,std::stold \- std::stof,std::stod,std::stold

.SH Synopsis
   Defined in header <string>
   float       stof ( const std::string& str, std::size_t* pos =      \fB(1)\fP \fI(since C++11)\fP
   nullptr );
   float       stof ( const std::wstring& str, std::size_t* pos =     \fB(2)\fP \fI(since C++11)\fP
   nullptr );
   double      stod ( const std::string& str, std::size_t* pos =      \fB(3)\fP \fI(since C++11)\fP
   nullptr );
   double      stod ( const std::wstring& str, std::size_t* pos =     \fB(4)\fP \fI(since C++11)\fP
   nullptr );
   long double stold( const std::string& str, std::size_t* pos =      \fB(5)\fP \fI(since C++11)\fP
   nullptr );
   long double stold( const std::wstring& str, std::size_t* pos =     \fB(6)\fP \fI(since C++11)\fP
   nullptr );

   Interprets a floating point value in a string str.

   Let ptr be an internal (to the conversion functions) pointer of type char* (1,3,5)
   or wchar_t* (2,4,6), accordingly.

   1) Calls std::strtof(str.c_str(), &ptr).
   2) Calls std::wcstof(str.c_str(), &ptr).
   3) Calls std::strtod(str.c_str(), &ptr).
   4) Calls std::wcstod(str.c_str(), &ptr).
   5) Calls std::strtold(str.c_str(), &ptr).
   6) Calls std::wcstold(str.c_str(), &ptr).

   Function discards any whitespace characters (as determined by std::isspace) until
   first non-whitespace character is found. Then it takes as many characters as
   possible to form a valid floating-point representation and converts them to a
   floating-point value. The valid floating-point value can be one of the following:

     * decimal floating-point expression. It consists of the following parts:

     * (optional) plus or minus sign
     * nonempty sequence of decimal digits optionally containing decimal-point
       character (as determined by the current C locale) (defines significand)
     * (optional) e or E followed with optional minus or plus sign and nonempty
       sequence of decimal digits (defines exponent to base 10)
     * hexadecimal floating-point expression. It consists of the following parts:

     * (optional) plus or minus sign
     * 0x or 0X
     * nonempty sequence of hexadecimal digits optionally containing a decimal-point
       character (as determined by the current C locale) (defines significand)
     * (optional) p or P followed with optional minus or plus sign and nonempty
       sequence of decimal digits (defines exponent to base 2)
     * infinity expression. It consists of the following parts:

     * (optional) plus or minus sign
     * INF or INFINITY ignoring case
     * not-a-number expression. It consists of the following parts:

     * (optional) plus or minus sign
     * NAN or NAN(char_sequence) ignoring case of the NAN part. char_sequence can only
       contain digits, Latin letters, and underscores. The result is a quiet NaN
       floating-point value.
     * any other expression that may be accepted by the currently installed C locale

   If pos is not a null pointer, then ptr will receive the address of the first
   unconverted character in str.c_str(), and the index of that character will be
   calculated and stored in *pos, giving the number of characters that were processed
   by the conversion.

.SH Parameters

   str - the string to convert
   pos - address of an integer to store the number of characters processed

.SH Return value

   The string converted to the specified floating point type.

.SH Exceptions

   std::invalid_argument if no conversion could be performed.

   std::out_of_range if the converted value would fall out of the range of the result
   type or if the underlying function (std::strtof, std::strtod or std::strtold) sets
   errno to ERANGE.

.SH Example

    This section is incomplete
    Reason: no example

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

      DR    Applied to         Behavior as published              Correct behavior
                       std::out_of_range would not be thrown
   LWG 2009 C++11      if the converted                       will throw
                       value would fall out of the range of
                       the result type
   LWG 2403 C++11      stof called std::strtod or std::wcstod stof calls std::strtof or
                                                              std::wcstof

.SH See also

   stoi
   stol
   stoll      converts a string to a signed integer
   \fI(C++11)\fP    \fI(function)\fP
   \fI(C++11)\fP
   \fI(C++11)\fP
   stoul
   stoull     converts a string to an unsigned integer
   \fI(C++11)\fP    \fI(function)\fP
   \fI(C++11)\fP
   from_chars converts a character sequence to an integer or floating-point value
   \fI(C++17)\fP    \fI(function)\fP

.SH Category:
     * Todo no example
